Sea ice altimetry

CPOM researchers use radar altimeter data from CryoSat to investigate ongoing changes in Arctic sea ice thickness and volume. Observations of sea ice volume are critical, as changes in volume impact the heat and freshwater budgets of the Arctic and have wider implications for the global climate. They also help us to improve our understanding of how sea ice behaves in terms of its mechanics, with particular emphasis on the factors that drive regional and interannual variations in ice thickness and volume.

In 2016, CryoSat showed that the Arctic had one of the lowest volumes of sea ice of any November, matching record lows in 2011 and 2012. Early winter growth of ice in the Arctic was about 10% lower than usual.

2011–16 November Arctic sea-ice thickness

The US National Snow and Ice Data Centre reported that the area of the Arctic covered by sea ice fell to 4.1 million sq km in September 2016 – slightly less than the sea-ice extent in September 2011.

But CryoSat shows that the ice was thicker at the end of summer than in most other years, at 116 cm on average. This means there was substantially more ice this year than in 2011.

However, the Arctic usually gains about 161 cubic km of ice per day in November, but 2016’s growth was been about 10% lower, at 139 cubic km per day, with a total ice volume estimated at 10,500 cubic km by the end of the month.

This would essentially tie with conditions in the Novembers of 2011, when levels were at their lowest on record for this time of the year.

Although sea ice in the central Arctic is currently thicker than it was in 2011, there is far less ice in more southerly regions such as the Beaufort, East Siberian and Kara Seas.

2011–16 November Arctic sea-ice volume. Credit: ESA

As demand for information on Arctic conditions increases, CryoSat has become an essential source of information for polar stakeholders, ranging from ice forecasting services to scientists studying the effects of climate change. CPOM provides near real time data on Arctic sea ice throughout the winter months.

As part of the project, CPOM researcher Rachel Tilling has participated in sea ice fieldwork campaigns organised by the ESA and the Finnish Meteorological Institute, using a sled-mounted radar to investigate the properties of snow on Arctic sea ice. Read Rachel’s blog about her Arctic adventures.